This application relates to adjustable louver systems and more particularly to louvers having a plurality of blades formed into hollow airfoil cross section and to rain resistant louver assemblies with means for minimizing water passing through the louver assembly.
Multiple blade louver systems to control air flow or light in architectural, heat exchanger, and solar light applications are well known. Industrial applications for louver systems to control air flow in factory and assembly plant areas are widespread. Louver assemblies are also commonly used adjacent large air-cooled heat exchangers and in cooling towers. Such systems due to the volume of the structures to be ventilated are generally large in size in order to control the high air flow rates through the system. Designers of louver blade assemblies appropriate for such applications have generally not addressed the aerodynamic implications of blade design as well as blade rigidity requirements to resist stress fatigue for louver blades under prolonged use.
Blades in common use for architectural purposes have not been designed with the objective of improving aerodynamic drag figures, consequently considerable energy is absorbed in the air stream wake at the trailing edge of the louver blade. Compensation for such energy absorption takes the form of high pressure drop through the louver assembly and thus increased power requirements for air fan drive motors resulting in an overall increase in the power supplied to the louver system as well as adding weight and therefore cost.
Another problem encountered with many louvers, particularly in high velocity air flows, such as above about 2,000 ft/min is that the blades not only interfere with the flow, but are noisy and rattle. To compensate for noise and the rattling, the blades are strengthened and made more rigid by increasing blade material thickness or by limitations on blade lengths. Both approaches restrict applicability of such louver blade systems because of the high weight and resulting material costs. If the weight increase is to be avoided, the blade length is limited, thereby increasing the number of parts required and increasing manufacturing and installation costs.
Prior art louver assemblies for preventing liquids such as rain water and atmospheric moisture from passing through the louver blade assembly, and therefore into the ventilated structure have particularly bad aerodynamics due to their convoluted shapes, resulting in extremely high power wastage, often several times the cost of a new louver in a year or so.